NSW has recorded 27 new local coronavirus cases, with a spike in infections expected again tomorrow as the outbreak grows to more suburbs.
Residents in three local government areas are being told to stay at home where possible and to avoid mingling with family.
There were 45,000 tests to 8pm yesterday, and the lockdown across Greater Sydney, Central Coast, Illawarra, Blue Mountains and Shellharbour has been extended another week.
READ MORE: Sydney lockdown extended by one week
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https://twitter.com/NSWHealth/status/1412577131339468806Breakdown of today's cases
NSW Chief Health Officer Dr Kerry Chant said of today's 27 local cases, 18 are linked to a known case or cluster.
Eleven are close contacts, and seven are household contacts of previously confirmed cases.
"As the premier has indicated, unfortunately we still are seeing a number of cases arise where they're infectious in the community for part or all of their infectious period," Dr Chant said.
"So only 13 of the cases - of the 27 cases - were in isolation throughout their infectious period.
"Seven cases were in isolation for part of their infectious period and seven cases were infectious in the community."
Dr Chant said the speed of the transmission of the Delta strain of COVID-19 meant by the time NSW Health identified a positive case, their entire household was also positive.
This is how some Sydney residents have been "unknowingly infectious" in the community.
Dr Chant said her concern is about a number of suburbs including Bossley Park, Smithfield, Fairfield, West Hoxton, Bass Hill, St Johns Park, Canley Vale and Greenfield Park.
She has asked residents of these suburbs to "double your efforts" and stay at home.
Three new areas of concern in Sydney
NSW Premier Gladys Berejiklian said tomorrow's figures are expected to spike again as the outbreak grows in three local government areas.
"I can foreshadow overnight that we've had a number of cases, more than we would like to have seen, so I'm anticipating that tomorrow's number will be higher than what we have seen today but they are at the moment concentrated in three local government areas," she said.
Ms Berejiklian urged people in Fairfield, Canterbury-Bankstown and Liverpool to stay at home and not mingle with family.
"Can I say to everybody don't mingle with family, don't think it is OK to visit your cousins or have sleepovers," she said.
"Please, in those three local government areas limit your movement.
"The New South Wales government doesn't want to go to the next stage but we are even considering if there are any further actions we need to take in those three local government areas.
"So can I just stress please, I know that you might think you are doing the right thing by visiting loved one, you might think you are doing the right thing by babysitting other's children or whatever but the key message in the Fairfield, Canterbury-Bankstown and Liverpool local government areas is please do not leave the house."
Dr Chant asked for residents to consider having groceries delivered or to only make "in and out" trips for essentials.
Students to learn from home
Students in Sydney will be learning from home next week as the lockdown is extended.
Ms Berejiklian confirmed schools will be closed to most students until Monday, July 19.
Children of essential workers will be allowed to attend school in person if necessary.
The order applies to schools in Greater Sydney, the Blue Mountains, Central Coast, Wollongong and Shellharbour.
Ms Berejiklian said no student would be turned away from school.
"Our strong preference is that parents keep children at home for home-schooling for the four days," she said.
"If they have no other option, the child is welcome on the school playground."
READ MORE: Remote learning for Greater Sydney schools
